This invention relates to fitting assemblies for anchoring aircraft passenger seatbacks to seat structures and more particularly, to a device which allows the seatback to rotate freely towards the seat structure, while remaining anchored to it, upon the application of an excessive external force on the seatback.
Seatback fitting assemblies must be safe, reliable and capable of positioning a passenger for comfort and safety for the duration of a flight. Under normal operating conditions, the entire seat configuration is subject to various loads and external forces, such as the weight and movement of an occupying passenger, or contact from others behind or near the seat.
Excessive dynamic loads on the seatback during a severe crash condition often exceed the structural strength required for normal operation and can contribute to the structural failure of the seatback. Further, under such crash conditions, the seatback is subject to being forcefully struck from behind by the head and/or body of another passenger, adding to any excessive dynamic load already acting on it. When such failure occurs, the seatback breaks off from the seat structure and carries itself dangerously into the cabin area. The torn seatback can become a missile causing serious injury, possibly lacerating passengers due to jagged edges formed in the torn anchorage. It could also hamper rapid evacuation of the aircraft. Thus, it is desireable that the seat remain structurally sound and that the seatback be capable of withstanding any excessive forces and remain anchored to the seat structure.
A variety of seatback fitting assemblies exist in the prior art. It is known for the fitting assemblies to have means for the seatback to be tilted forward within a limited range of motion, typically around fifteen degrees. This is accomplished by the use of a friction clutch, which normally retains the seatback in a fixed position, but may be overcome by a force exerted upon the seatback. The seatback may then be moved forward until the clutch mechanism prevents further tilt, typically by means of an "anchor point." This "tilt capability" is useful to expedite cleaning of the aircraft cabin, e.g., a cleaning crew member merely pushes the top of the seatback to move it into a forward tilt position, without needing to unlock the seatback from the fitting assembly. However, the seatback anchorage of those seats which feature this limited forward tilt capability may fail at load levels substantially lower than those experienced in a severe crash.
The present invention is directed at eliminating the safety problems experienced in the prior art due to the structural failure of seatbacks caused by excessive dynamic loads and/or passenger impacts under severe crash or similar conditions. Further, the present invention reduces the potential injuries to the occupant of a seat behind the seatback of this invention by limiting the reaction load experienced by such occupant impacting the seatback.